1. Field of the Invention
The present invention relates to a face identification apparatus, a face identification method, and a face identification program for identifying a face of an object person of an image object; and particularly, to the face identification apparatus, the face identification method, and the face identification program for judging whether or not a facial region (face region) expected in an image (taken image), which is obtained by imaging the object person, is suitable, and identifying the face of the object person, based on the facial region (face region) judged suitable.
2. Description of the Related Art
These years there are proposed many methods and apparatuses thereof for identifying an object person from an image where the object person is taken by a video camera (hereinafter simply referred to as ‘camera’) such as a CCD (Charge Coupled Device) camera.
As conventional technologies of this kind, there are ones as follows: a patent document 1, Japanese Patent Laid-Open Publication Hei No. 09-251534 (paragraph 0021); a patent document 2, Japanese Patent Laid-Open Publication Hei No. 10-232934 (paragraph 0023 and FIG. 1); and a patent document 3, Japanese Patent Laid-Open Publication Hei No. 11-015979 (paragraphs 0015 to 0031 and FIG. 2).
Inventions described in these patent documents extract a facial region (face region) from an image obtained by imaging an object person, dispense normalization processing to the face region, making features such as eyes and a mouth included in the extracted face region, and thus make a normalized face regional image (normalization face image). And the inventions compare/collate the normalization face image with a dictionary image prepared in advance and recognize/identify the object person.
The inventions described in the patent documents 1 and 2 perform the extraction of the face region by calculating a correlation value while moving a standard face image (template) across a whole screen of the image and regarding the highest region of the correlation value as the face region.
In addition, the invention described in the patent document 3 performs the extraction of the face region by searching a flesh-color region and a dark region in the image and regarding the flesh-color region, where the dark region is included at a constant ratio within the flesh-color region, as the face region.
But because when an object person is moving or an imaging of the object person is performed while moving, a position relationship between a light source and the object person changes, in some case a shade enters in the face of the object person within the image and the extraction of the face region is not adequately performed, receiving an influence of the shade.
In such the case the inventions described in the patent documents recognize/identify the object person without judging whether or not the extracted face region is suitable for the recognition/identification of the object person. Accordingly, when an inadequate face region is extracted, the inventions result in recognizing/identifying the object person, based on the inadequate face region, and there occurs a problem that these cannot accurately recognize/identify the object person.
Consequently, there is a strong request for a method and an apparatus that do not generate such the problem.